High voltage fuse links having flexibly mounted fuse support



E. JAcKs ETAL 3,270,168

HIGH VOLTAGE FUSE LINKS HAVING FLEXIBLY MOUNTED FUSE SUPPORT Aug. 3o', 196e Filed May 14, 1964 FIG.2

United States Patent O 3,270,168 HIGH VOLTAGE FUSE LINKS HAVING FLEXIBLY MOUNTED FUSE SUPPORT Eric Jacks, John Feenan, and George William Ollerton, Liverpool, England, assignors to The English Electric Company Limited, London, England, a British company Filed May 14, 1964, Ser. No. 367,527 Claims priority, application Great Britain, May 20, 1963, 19,881/ 63 7 Claims. (Cl. 200--132) The invention relates to high voltage electric fuse links.

According to the invention, there is provided a high voltage fuse link comprising a hollow fuse body, an end cap yat each end of the fuse body, a core member within the fuse body spaced therefrom by a surrounding gap, electrical terminal means at each end of the core member, at least one fuse element supported by the core member and connected between the two terminal means, supporting means at each end of the fuse body connected between the core member and the respective end cap, at least one supporting means providing a resilient mechanical connection between the core member and the respective end cap for at least partially supporting the core member with respect to the end cap, and electrical connection means providing an electrical connection between each terminal means and the respective end cap.

Preferably, the fuse link includes granular filler, having arc inhibiting properties, filling the said surrounding gap and partially supporting the core member.

In an embodiment of the invention, the said one supporting means comprises a locating member having a tapered end adapted to engage resiliently in a tapered bore in one end of the core member and a cylindrical end adapted to engage rigidly with a complementary part on the respective end cap.

Advantageously, the said complementary part on the respective end cap is a portion thereof which extends inwardly into the fuse body, the cylindrical end of the locating member being adapted to be a tight press it on the inwardly extending portion of the end cap.

Preferably, the locating member is electrically conductive and one of the said electrical connection means comprises one or more flexible conductive strips connecting the terminal means at the end of the core member engaged by the locating member with the locating member.

Each terminal means may comprise a cap over the respective end of the core member, at least one of the caps having a central hole as necessary for permitting entry of the locating member.

A fuse link embodying the invention will now be described by way of example and with reference to the accompanying drawings in which:

FIG. 1 is a cross sectional view of one end of the fuse link, the other end being the same; and

FIG. 2 is an elevation of one end of the inside par-ts of the fuse link.

The fuse link comprises a hollow fuse body 10 surrounding a ceramic former 11 upon which are wound a number of fuse elements 12. The former 11 is commonly known as a star core and has projecting ribs 11A. The annular space between the fuse body 10 and the star core 11, and also the bore of the star core, are filled with granular filler 13. The elements 12v are spot welded to an inner cap 14 which is itself cemented to plaster 15 iilling the spaces between the ribs 11A at the end of the star core. A resilient tapered bung or sleeve 16 is inserted in the star core to provide a loose sli-ding iit for a corresponding tapered end of a hollow locating member 17.

The locating member 17 is lexibly or resiliently coupled to the star core cap 14 by four equi-spaced interconnect- 3,270,168 Patented ugust 30, 1966 ice ing links 18 of silver strip. The links 18 are disposed axially -along the end of the locating member 17 remote from the star core and radially across a radially inwardly extending portion of the star core cap 14 and are spot welded at their ends to the locating member 17 and the star core cap 14 respectively. An asbestos washer 19 is interposed between the member 17 and the star core cap 14. The projection 17 carries at its narrow end a tag 20 for the attachment of a striker coil 21, and is recessed at its wider end so as to be a press tit on an inwardly extending portion of an end cap 22 which is mounted on the end of the fuse body 10. The member 17 has slots 17A to facilitate its iitting on to the end cap 22. The endcap 22 abuts a spacing washer 23 within the hollow member 17. The centre of the spacing washer 23 is iilled with packing 24. The part of the member 17 which engages with the tapered bung 16 is filled with further packing.

On assembly, the star core cap 14 is first cemented to the star core and the fuse elements are then spot welded to the star core cap.

It will be apparent that the resilient mounting between the star core cap 14 and the end cap 22 of .the fuse body, as provided by the member 17 and the bung 16, provides compensation for any misalignment between the star core and the end caps 22 during assembly. In addition, the fuse elements are attached to the star core cap 14 which is itself attached -to the star core so that there will be no tendency for the fuse elements to be put under strain during assembly.

Methods of rigidly engaging the star core caps with the end caps of the fuse body often produce some dithculty in locating the star core caps accurately with the end caps during assembly, and the star core caps tend to be moved slightly before reaching alignment with the end caps. It is often found that, 'as a result of lthis movement, the flexible fuse elements which are secured to the star core caps are put under strain and may break, and actual breakage of the ceramic star core itself may occur. Even when breakages do not occur, the elements are under strain and this impairs their short circuit performance. The flexible mounting between the star core and the end caps of the fuse body, as provided by the invention, avoids these disadvantages.

What we claim as our invention and desire to secure by Letters Patent is:

1. A high voltage fuse link comprising a tubular fuse body having a rst pair of terminal caps secured to opposite ends thereof,

an insulating core member having Ia second pair of terminal caps secured to opposite ends thereof,

a fuse element supported by the core and connected between said second terminal caps,

a pair of conductive sleeves,

irst resilient means mounting the opposite ends of the core on said sleeves, and

second resilient means respectively connecting the sleeves to said second terminal caps, Ithe first terminal caps lying in engagement with said sleeves whereby to support the core within the tubular fuse body.

2. A fuse link according to claim 1, wherein said insulating core is tubular and defines a bore extending axially throughout its length, each said sleeve comprising a lirst portion disposed within the bore of the core, and

a second portion disposed externally of the core, said second resilient means lying within the bore, between, and in engagement with, the said core and the said second portion of the sleeve.

3. A fuse link according to claim 2, wherein the said second resilient means and said second portion of the angle of taper.

4. A fuse link according to claim 2, wherein each of said rst terminal caps comprises a first portion engaging -the exterior of said tubular fuse body, and a second portion extending inwardly within said body, said second portion of the sleeve embracing the said second portion of the first terminal cap and being in frictional engagement therewith. 5. A fuse link according to claim 2, comprising an auxiliary fusible striker coil secured to said second portion of the sleeve and extending along said bore. 6. A fuse link according to claim 1, wherein said rst resilient means comprises a plurality of flexible conductive strips spaced apart from one another.

7. A high voltage fuse link comprising, a tubular fuse body having a first pair of terminal caps secured to opposite ends thereof, an insulating core member star-shaped in cross-section and having a second pair of terminal caps secured to opposite ends thereof, a fuse element wound about, and supported on, said core and secured between the said second terminal caps,

a pair of conductive sleeves,

rst resilient means mounting the opposite ends of the core on said sleeves,

second resilient means respectively connecting the 5 sleeves lto said second terminal caps, the rst terminal caps lying in engagement with said sleeves whereby to support the core within the tubular fuse body, and

a mass of arc-inhibiting granular material filling the 10 interior of said fuse link.

References Cited by the Examiner UNITED STATES PATENTS 2,216,661 10/1940 Dannenberg 200-120 2,639,350 5/1953 COX 200--120 FOREIGN PATENTS 9/ 1938 Great Britain. 

1. A HIGH VOLTAGE FUSE LINK COMPRISING A TUBULAR FUSE BODY HAVING A FIRST PAIR OF TERMINAL CAPS SECURED TO OPPOSITE ENDS THEREOF, AND INSULATING CORE MEMBER HAVING A SECOND PAIR OF TERMINAL CAPS SECURED TO OPPOSITE ENDS THEREOF, A FUSE ELEMENT SUPPORTED BY THE CORE AND CONNECTED BETWEEN SAID SECOND TERMINAL CAPS, A PAIR OF CONDUCTIVE SLEEVES, FIRST RESILIENT MEANS MOUNTING THE OPPOSITE ENDS OF THE CORE ON SAID SLEEVES, AND SECOND RESILIENT MEANS RESPECTIVELY CONNECTING THE SLEEVES TO SAID SECOND TERMINAL CAPS, THE FIRST TERMINAL CAPS LYING IN ENGAGEMENT WITH SAID SLEEVES WHEREBY THE SUPPORT THE CORE WITHIN THE TUBULAR FUSE BODY. 